Nanostructuring at oblique incidence deposition of cobalt

Nanocolumnar Co thin films growth by oblique angle deposition on Si substrate is experimentally studied. Formation of regular arrays of tilted Co nanocolumns has been observed at incidence angles more than 70°. It was found that the optimal conditions for nanostructuring are realized at the inclination angle 85°. As obtained films have magnetic anisotropy axis inclined to the substrate surface and oriented along nanocolumns. Such films might be perspective material for applications as a magnetic recording media for next generations of hard disks.

Fabrication of a Chalcogenide Glass Microlens Array for Infrared Laser Beam Homogenization

Infrared (IR) microlens arrays (MLA) have attracted increasing interest for use in infrared micro-optical devices and systems. However, the beam homogenization of IR laser light is relatively difficult to achieve because most materials absorb strongly in the IR wavelength band. In this paper, we present a new method for the application of double-sided quasi-periodic chalcogenide glass (ChG) MLAs to infrared laser homogenization systems. These are non-regular arrays of closely spaced MLAs. The double-sided MLAs were successfully prepared on the ChG surface using a single-pulse femtosecond laser-assisted chemical etching technique and a precision glass molding technique. More than two million close-packed microlenses on the ChG surface were successfully fabricated within 200 min. By taking advantage of ChG’s good optical performance and transmittance (60%) in the infrared wavelength band (1~11μm), the homogenization of the IR beam was successfully achieved using the ChG quasi-periodic MLA.

Multipolar Lattice Resonances in Plasmonic Finite-Size Metasurfaces

Collective lattice resonances in regular arrays of plasmonic nanoparticles have attracted much attention due to a large number of applications in optics and photonics. Most of the research in this field is concentrated on the electric dipolar lattice resonances, leaving higher-order multipolar lattice resonances in plasmonic nanostructures relatively unexplored. Just a few works report exceptionally high-Q multipolar lattice resonances in plasmonic arrays, but only with infinite extent (i.e., perfectly periodic). In this work, we comprehensively study multipolar collective lattice resonances both in finite and in infinite arrays of Au and Al plasmonic nanoparticles using a rigorous theoretical treatment. It is shown that multipolar lattice resonances in the relatively large (up to 6400 nanoparticles) finite arrays exhibit broader full width at half maximum (FWHM) compared to similar resonances in the infinite arrays. We argue that our results are of particular importance for the practical implementation of multipolar lattice resonances in different photonics applications.

The yeast ISW1b ATP-dependent chromatin remodeler is critical for nucleosome spacing and dinucleosome resolution

Isw1 and Chd1 are ATP-dependent nucleosome-spacing enzymes required to establish regular arrays of phased nucleosomes near transcription start sites of yeast genes. Cells lacking both Isw1 and Chd1 have extremely disrupted chromatin, with weak phasing, irregular spacing and a propensity to form close-packed dinucleosomes. The Isw1 ATPase subunit occurs in two different remodeling complexes: ISW1a (composed of Isw1 and Ioc3) and ISW1b (composed of Isw1, Ioc2 and Ioc4). The Ioc4 subunit of ISW1b binds preferentially to the H3-K36me3 mark. Here we show that ISW1b is primarily responsible for setting nucleosome spacing and resolving close-packed dinucleosomes, whereas ISW1a plays only a minor role. ISW1b and Chd1 make additive contributions to dinucleosome resolution, such that neither enzyme is capable of resolving all dinucleosomes on its own. Loss of the Set2 H3-K36 methyltransferase partly phenocopies loss of Ioc4, resulting in increased dinucleosome levels with only a weak effect on nucleosome spacing, suggesting that Set2-mediated H3-K36 trimethylation contributes to ISW1b-mediated dinucleosome separation. The H4 tail domain is required for normal nucleosome spacing but not for dinucleosome resolution. We conclude that the nucleosome spacing and dinucleosome resolving activities of ISW1b and Chd1 are critical for normal global chromatin organisation.

Направление диффузионного потока галлия при осаждении на поверхность с регулярными массивами отверстий

Self-catalyzed growth of GaAs and GaP nanowires by molecular beam epitaxy is often performed on processed SiOx/Si(111) substrates with regular arrays of lithographically defined holes. Ga droplets form in the holes during Ga pre-deposition step in the absence of As supply. It was considered evident that the Ga diffusion flux in such a process is directed from the oxide surface into the holes. Here, we show that it is not always true and that the diffusion flux can change its direction depending on the growth conditions. Our model can be useful for modeling the incubation and growth times of group III droplets within the holes and explains long nucleation delays of the droplets.

Наноструктурирование при наклонном напылении алюминия

Formation of regular arrays of nanorods with high aspect ratio (length to transverse size) has been found in the process of Al thin film growth at oblique angle deposition on silicon substrate by the method of electron beam evaporation. It was found that the optimal conditions for nanostructuring are realized at the inclination angle larger than 80 degrees.

Development of a polystyrene colloidal monolayer processin the technology of microsphere lithography

The study introduces an operation of deposition of a polystyrene microspheres monolayer from a colloidal suspension, based on the Langmuir ― Blodgett method. The operation plays a key role in the technology of microsphere lithography. The paper describes the laboratory equipment developed to produce ordered colloidal films and monolayers, shows the main modes of the process, and presents the results of studying the surfaces of samples using an atomic force microscope. Findings of research show that the films obtained are close-packed monolayers of microspheres in accordance with the hexagonal symmetry, which are suitable to be used as templates. By means of them and by the method of microsphere lithography, it is possible to obtain regular arrays of nanoparticles of a given size for products of photonics, sensorics, and nanoelectronics.